Season Roundup: Cellular Respiration

This season, we focused on enzymes and cellular respiration. On Friday, October 14th, we continued our yeast catalase lab where each of the four groups tested the effects of pH, concentration, and temperature of enzymes on yeast catalase activity. To determine the effects of pH, HCl (an acid) and NaOH (a base) were added to the yeast solution and see how the pH affected the rate of the reaction. To determine the effects of concentration, different proportions of yeast catalase solution were used and with an increase of concentration, the rate of reaction was also increased. To determine the effect of temperature, the yeast catalase solution was heated or cooled down and the temperature of the solution was recorded. With an increase of temperature, the rate would peak at around room temperature, and either heating or cooling should decrease the rate of this reaction. To summarize our findings, each group created a lab report folder and afterwards, each group visited each of the other groups’ folders to learn about their findings.

Kyla, Helen, and Keira are working on determining the effects of concentration of yeast catalase
Photo courtesy of Rebecca Girard

Several groups are working on putting their lab report folders together!

Then, we took a five day break from school; however, biology never takes a break and we needed to save Jared! Jared was a CIA agent who was poisoned on a top secret mission, and this poison inferred with his ability to make ATP. Without ATP, his cells would stop working. Using our knowledge on cellular respiration, we needed to determine which of the four toxins Jared was poisoned with. To do so, we used healthy muscle tissue as control data and saw the  different effects from pyruvate, NADH, and IM protons on Jared’s muscle tissue. Jared’s tissue had no change from healthy muscle tissue in pyruvate levels, his NADH levels strongly increased, and the levels of his IM protons decreased. We then tested four toxins on healthy muscle tissue and saw how each of these affected the pyruvate, NADH, and IM proton levels. We were able to conclude that cyanide was the toxin in which Jared had ingested as cyanide was the only toxin that also resulted in the same changes of these levels in comparison with Jared’s muscle tissue. We were then able to save Jared!

Save Jared (program by Cogent Education)

If you’re confused about cellular respiration, you’re not alone! While my classroom was waiting to start the ACT the past weekend, two people were having a conversation about how they were completely lost within this complicated biology topic! We just need to make sure to work together and ask questions to enhance our understanding. To begin, the equation for cellular respiration is C6H12O6+6O2+6H2O —>12H2O+6CO2+32-38ATP. This equation is the reverse of the equation for photosynthesis, which makes sense as plants ingest carbon dioxide and sunlight energy to produce glucose. Cellular respiration has three components: Glycolysis, The Krebs Cycle/The Citric Acid Cycle, and the Electron Transport Chain. These components work independently from each other, which we were able to determine from saving Jared, but they also build off of each other and the products each component makes. The purpose of glycolysis is to split glucose and produce two pyruvate molecules. The purpose of the Citric Acid Cycle is to take the pyruvate and use it to help produce ATP, NADH, and FADH2. NADH and FADH2 are electron carriers, which are then used in the Electron Transport Chain, where its main purpose is to produce ATP. We listed to an MP3 tutor to help create this brochure to summarize the processes that take place within aerobic cellular respiration, and I included a copy of mine below.

3 components of cellular respiration:
glycolysis, the citric acid cycle, and the electron transport system

This short span of a couple days have been brain packed with labs, simulations, and lecture, but we pulled through! Now onto a season of photosynthesis!